1. Field of the Invention
The present invention relates to a light-emitting device, a lighting device and an electronic device incorporating the light-emitting device, and a method for manufacturing the light-emitting device, and more particularly, to a light-emitting device including a light-emitting element and including a structure that indicates the arrangement of the anode and the cathode of the electrodes of the light-emitting element.
2. Description of the Related Art
A Light-emitting device (hereinafter referred to as the light-emitting device) including a light-emitting element that is a semiconductor element has been widely used. Such a light-emitting device can achieve a long service life, outstanding driving characteristics, a compact size, and an efficient emission of light, and even can provide vivid emission of light in various colors including white. Due to these features of light-emitting device including a light-emitting element such as a light-emitting diode element (LED element), light-emitting devices including LED elements have been widely used in applications such as backlights for color display devices lamps, lighting tubes or lighting systems. In particular, these days, to cope with reductions in the size of the parts to be mounted on portable devices such as cellular phones or personal digital assistants, there has been an increasing demand for reducing the size of the mounting structure of the light-emitting device to be incorporated into the portable devices.
On the other hand, the light-emitting device having an LED element is known to be constructed in a manner such that the LED element is mounted on a patterned electrode formed on a substrate, and then this LED element is sealed on the upper surface of the substrate with a light-transmitting resin. In the step of mounting this light-emitting device, the polarity of the electrodes of the light-emitting device has to be identified, for example, when the light-emitting device is mounted onto a feed tape, when the light-emitting device is automatically mounted on the motherboard (printed circuit board) of an electronic device onto which the light-emitting device is to be mounted, or when the light-emitting device mounted on the motherboard is visually checked. Accordingly, conventional light-emitting devices are provided with a polarity mark for identifying polarities (for example, FIGS. 1 and 2 in Japanese Patent Application Laid-Open No. 2008-258455, and FIGS. 2 and 3 in Japanese Patent Application Laid-Open No. 2009-152482.)
FIGS. 13 and 14 show a light-emitting device 100 disclosed in FIGS. 1 and 2 in Japanese Patent Application Laid-Open No. 2008-258455. The light-emitting device 100 includes a substrate 110 having a pair of electrodes as an anode electrode 112 and a cathode electrode 111; an LED element 50 disposed with the cathode element electrode of the LED element 50 in contact with the cathode electrode 111 of the substrate 110; a wire 116 connected from the anode element electrode provided on the upper surface of the LED element 50 to the anode electrode 112 of the substrate 110; and a light-transmitting resin 113 that seals the LED element 50.
The cathode electrode 111 and the anode electrode 112 mentioned above extend from the upper surface of the substrate 110 to the lower surface via the side surfaces. Furthermore, the upper surface of the substrate 110 is provided with a pair of polarity marks 115 which are formed, outside the sealing range of the light-transmitting resin 113, by cutting a part of the cathode electrode 111 that is provided on the upper surface of the substrate 110. These polarity marks 115 are intended to be used to identify the orientation of the electrodes when the light-emitting device 100 is mounted on an external motherboard such as of an electronic device. As described above, outside the sealing range of the light-transmitting resin 113, the cathode electrode 111 is provided on the upper surface of the substrate 110 with the polarity marks 115, and thus, it is easier to recognize the orientation of the electrodes.
Furthermore, FIG. 15 shows a light-emitting device 200 disclosed in FIG. 2 in Japanese Patent Application Laid-Open No. 2009-152482. The light-emitting device 200 includes a substrate 210; a cathode electrode 211 and an anode electrode 212 which are formed on the substrate 210; an LED element 50 disposed at the center of the substrate 210; a wire 216a connecting between the cathode element electrode of the LED element 50 and the cathode electrode 211 of the substrate 210; a wire 216b connecting between the anode element electrode of the LED element 50 and the anode electrode 212 of the substrate 210; and a light-transmitting resin 213 for sealing the LED element 50.
The cathode electrode 211 provided on the substrate 210 extends to the lower surface of the substrate 210 via a through-hole 211b and is then electrically connected to a lower surface electrode 211a on the lower surface. Furthermore, the anode electrode 212 provided on the substrate extends to the lower surface of the substrate 210 via a through-hole 212b and is then electrically connected to a lower surface electrode 212a on the lower surface. Furthermore, between the opposing outside surfaces of an optically transparent resin 213 and both the sides of the LED element 50, there are each provided a deep groove 213a that reaches the upper surface of the substrate 210. The wall surface of a reflective white resin 214 filled in the deep groove 213a forms a white reflective frame 214a surrounding the LED element 50 . There is also formed a shallow groove 213b in the vicinity of the outside of one of the two deep grooves 213a provided on both the sides of the LED element 50, the groove 213b forming part of the reflective frame 214a, and the shallow groove 213b is filled with the reflective white resin 214 that provides a wall surface 215. The provision of the wall surface 215 enables one to recognize the arrangement of the cathode electrode 211 and the anode electrode 212 on the substrate 210.
However, the aforementioned light-emitting device 100 is configured to have the substrate 110 on which the LED element 50 is mounted and the polarity marks 115 which are provided outside the sealing range of the light-transmitting resin 113 for sealing the LED element 50 on the upper surface of the substrate 110. Thus, although the orientation of the electrodes can be easily recognized when the light-emitting device 100 is mounted on an external board, the size of the substrate 110 becomes larger than the sealing range of the light-transmitting resin 113. This will lead to an increase in the size of the light-emitting device 100 itself and cannot meet the demand for reducing the size of parts.
On the other hand, the aforementioned light-emitting device 200 has the substrate 210 on which the LED element 50 is mounted, and the polarity mark 215 which is formed in the upper surface of the optically transparent resin 213 for sealing the LED element 50 on the upper surface of the substrate 210. Thus, like the light-emitting device 100 mentioned above, the orientation of the electrodes can be identified with ease when the light-emitting device 200 is mounted on an external substrate. However, after the light-emitting device 200 has been completed, this structure requires an extra step of forming the additional shallow groove 213b in the optically transparent resin 213 with the reflective white resin 214 filled in the groove 213b, which is necessary to be disposed outside the white reflective frame 214. Accordingly, the size of the optically transparent resin 213 tends to be larger because of the groove 213b provided outside the white reflective frame 214, and this will lead to an increase in the size of the light-emitting device 200 itself.